Why does it say no access to QB files, even though the owner has granted access?

Hello aneesa-bibi-prof,

Welcome to the QuickBooks Community. It's important you're able to access your files with ease and I'll be glad to point you in the right direction so you can achieve your goals with ease. 

I'd like to start off by troubleshooting this issue to determine if it's a browser-related issue. Clearing cache and cookies is a great way to clean your browser allowing it to work more efficiently. Here's an article that shows you how to do that: How to clear cache and cookies. If this doesn't work, I suggest using a private/incognito window to see if that works instead. Try this out and let me know what happens. Here's a helpful article with more info about: User Roles in QuickBooks. 

Let me know if this info helps in the comments below. I'll be one message away in case you need further assistance.